"This is the mistake of people thinking [terrorism] suddenly began in the past couple of years," Blair said. "The roots of this were deep. The terrorist attacks go back over 10 years, and the way of defeating it is to defeat it, of course, by security measures but also by going after the ideas of these people, the ideology of these people, their arguments as well as their methods."
Chatham House -- formally known as the Royal Institute of International Affairs -- said Britain is increasingly exposed to terrorist attacks because of its close alignment with the United States on Iraq policy. It also said the Iraq war makes it easier for groups like Al-Qaeda to recruit new members.
In Washington, Anthony Cordesman, a former intelligence analyst with the Pentagon and the State Department, said that conclusion has only minimal validity.
Cordesman told RFE/RL that Britain might be slightly more vulnerable, but he said resentment of Western policies has been building up for years among Islamic militants, even before the attacks of 11 September 2001 in the United States.
"Any of the countries that were involved in dealing with the threat of Islamist extremism became potential targets," Cordesman said. "It didn't take Iraq to make that an issue. And long before [the 11 September attacks] you saw Islamist extremist attacks in places like France, Germany, and other countries. You also saw the buildup of various cells and groups in Britain -- almost the center for a lot of the groups which couldn't operate in other European countries or in the Middle East."
Cordesman said the U.S. and British military presence in Iraq has likely had an effect on recruitment of Muslim militants. But he said it feeds on longstanding popular resentment of Western support for governments in predominantly Muslim countries that are viewed as corrupt.
"Certainly [the U.S.-British alliance in Iraq has a role] in this [recruiting militants], but when you have movements which were attempting to attack virtually every moderate or secular government in the Middle East, which were already trying to dominate Islamic communities in Europe and having a significant influence in part of the Islamic communities in the United States, many of these problems and tensions and indeed acts of violence were going to surface regardless," Cordesman said.
Another Washington analyst, Nathan Brown of the Carnegie Endowment for International Peace, gave more credence to the Chatham House findings. He said Al-Qaeda and like-minded groups are adept at using the media to stir resentment in the Muslim world.
"I think there is some sense to that [the Chatham House report], that Britain's stand with Iraq probably does raise its attractiveness or profile as a target," Brown said. "I think it probably helps [terrorist groups] recruit a little bit, and they're also fairly media savvy. Their audience is primarily in the religious parts of the Muslim world, and for them Iraq has some salience."
But Brown told RFE/RL that Muslim resentment of the West dates back to long before the Iraq war or 11 September. Like Cordesman, he pointed to terrorist attacks that go back years.
Still, he said, the Iraq war's influence on angry Muslims will have a much broader impact over the years.
"It's not necessarily going to create Al-Qaeda; Al-Qaeda existed before," Brown said. "But what it will do is, over the long term, convince those people who are already fairly hostile toward the United States to see it as an immediate threat, rather than as just sort of a distasteful external actor."
Brown said that perception of the United States and its closest ally, Britain, eventually could make both countries significantly more vulnerable.